Artificial respirator



J. H. EMERSON ARTIFICIAL. RESPIRATOR Dec. 18, 1956 5 Sheets-Sheet 1 Filed May 51, 195

Mew?" @Izmflirrzeraaw Dec. 18, 1956 J. ON 2,774,348

ARTIFICIAL RESPIRATOR Filed May 31, 1952 3 Sheets-Sheet 2 Dec. 18,1956 J. H. EMERSON 2,774,348

ARTIFICIAL RESPIRATOR Filed May 51. 1952 3 Sheets-Sheet 3 United States Patent O ce ARTIFICIAL RESPIRATOR John H. Emerson, Arlington, Mass.

Application May 31, 1952, Serial No. 290,856

23 Claims. (Cl. 128-30) This invention relates to apparatus for producing artificial respiration in a patient and more particularly to the type of artificial respirator where the patients chest and/or abdomen are enclosed in a casing and are subjected to alternating negative and substantially atmospheric or positive pressures to assist him to breathe under conditions where either the patient, by himself, is capable of initiating inhalation but is incapable of adequately completing it, as for example in bulbar polio cases or in polio cases where the patients breathing muscles are not completely paralyzed. In some aspects the apparatus of this invention is also capable of use with a patient who is completely incapable of initiating any breathing action whatsoever as in polio cases where the patients muscles are completely paralyzed.

One object of the invention is to provide an artificial respirator which is pneumatically controlled either by the patient himself or by a pneumatic system which is operated by variations of pressure within the respirator casing.

Another object is to provide an artificial respirator wherein the patient himself controls the initiation of the commencement of the negative pressure cycle when he consciously or subconsciously initiates inhalation.

Another object is to provide an artificial respirator wherein the patient himself initiates the commencement of both the negative pressure or inhalation period and the atmospheric or positive pressure or exhalation period when he initiates inhalation and initiates exhalation.

A further object is to provide an artificial respirator with two pneumatic controls, one operated by the patient himself when he initiates inhalation and the second operated by a pneumatic system connected with the interior of the casing so that the latter pneumatic control functions in the event the patient becomes unable to initiate inhalation or in the event the first pneumatic control fails to function for any other reason.

Another object of the invention is to provide an artificial respirator with a novel pneumatic control.

A further object of the invention is to provide a pneumatic control for an artificial respirator which is so sensitive that the patient can operate it himself by the subconscious initiation of an inhalation without any noticeable efiort and without being conscious of himself con-'- trolling the apparatus.

Fig. 2 is a side elevation similar to Fig. 1 with part of 2,774,348 Patented Dec. 18, 1956 the respirator casing broken away and shown in vertical section, and showing the position of the patient and alternate means by which the patient-initiated control device maybe interconnected to the patient;

Fig. 3 is an enlarged elevation of a pneumatically operated switch for one embodiment of pressure control device embodying the invention;

Fig. 4 is a rear elevation of the device of Fig. 3;

Fig. 5 is an enlarged side elevation of the device of Fig. 3 with parts shown in vertical section;

Fig. 6 is a schematic view of the device for creating variations of pressure within a respirator casing including a patient-initiated control for the pressure creating device;

Fig. 7 is a schematic view of another embodiment of the invention showing the combination of a patientinitiated control and an automatic control, the patientinitiated control being normally utilized and the auto matic control becoming operative if the patient control' fails.

Referring to Figs. 1, 2 and 6 of the drawings, the respirator is here shown by way of example as comprising the usual substantially air-tight respirator casing 1 which forms an enclosure for the patients body up to his neck.

The patient reclines upon a horizontal bed 2 (Fig. 2) within the casing and his neck extends through a restricted orifice in a collar 3 of sponge rubber material at the end 4 of said casing, his head resting upon the headrest 5 and exposed to the atmosphere. It is to be understood, however, that the enclosure for the patients chest may comprise a conventional chest respirator wherein the substantially air-tight casing forms an enclosure for at least part of the patients chest. Such a respirator sometimes encloses the entire chest, sometimes part of the chest and part of the abdomen.

Beneath the opposite end of the respirator a compartment 6 (Fig. 1) is provided in which is disposed an apparatus schematically shown in Fig. 6 and which includes a negative pressure conduit 10 communicating at one end with the interior of the respirator casing through the conduit 100. At the opposite end 11 of the conduit 10 a motor operated suction blower 12 of any desired construction is provided for continuously creating negative pressure within the negative pressure conduit 10. An atmospheric conduit 13 communicates with the delivery conduit means 100 and thus with the interior of the casing 1 and with the atmosphere through the port 14. The exhaust tube 15 extends from the suction blower 12 into the atmospheric conduit 13 and it is provided at the end ad-' jacent to the port 14 with a venturi 17 having a restricted orifice. provided in the atmospheric conduit 13.

The valve 18 is opened and closed by suitable means here shown as a double acting solenoid 20 which is energized by one circuit to close the valve and energized by another circuit to open the valve as will hereinafter be described.

When the valve 18 is closed, the suction blower 12 creates negative pressure in the negative pressure conduit 10 and in the respirator casing 1 and this negative pressure causes expansion of the patients chest and lungs and thus causes an inhalation. When the valve 18 is opened the exhaust air from the suction blower which has'up to this point passed out to the atmosphere through the atmos phere port 14, passes through the conduit 13 to the casing 1. When it passes through the venturi 17 it draws in air through the atmosphere port 14 thereby increasing the volume of gas transmitted to the casing and more rapidly neutralizing the negative pressure in the casing and building up the pressure therein to atmospheric or positive. This variation in pressure acts upon the patients chest and creates a forced exhalation.

An electrically operated butterfly valve 18 is The negative pressure conduit 10 is provided with an atmospheric pressure gas inlet port 21 providing comrnunicatin between the atmosphere and the interior of the negativetpressure conduit 10, thein-flowof air being controlled by a suitable valve22 hereoshownforexample as comprising a cylindrical casing-23, having a central bore 24, the inner end of the casing constitutingavalve seat 25. A disk 2 6 constituting a valve is 'sh'oivn in seated position and is resiliently urged outwardly to scatedupolsition by means of a helical spring 27'having its inner: end in contact with the outer. end of thecasingZE'and its outer end engaging the headflgi of a stem 29 fast to: the disk;

7 This is'a safety valve and it opens only when th'enegative pressure Within the conduit lllfeigceeds a predetermin d 7 amount; in which event the'valve 22fis' rnoyed*iifn vardly m s ih pr g: nd; i itt und r mo pheric -pressure to the conduit 10 and thereby decreasing the amount of negative;pressure in the conduit until the 'spring returns the valve to its normal seatedfposition.

stantially;atmospheric pressurer Accordinglyathis valve functions asa. leakfor positive pressure and by adjusting the amount. it can open, the size of;theleak-*is'controlled c andlthe-maximurn positive pressurewhichcanbe created 7 inthe casing-isjlikewisescontrolledr V SuppQrtedxon .a bracket-40 of the headrest S by suit able; vmeans such as. a book 41: is a pneumatic switch 42 (Eigs lgto, 6cinclusive) comprising a housing; formed by preferably disklshapegl front'and rear plates 44-andj45 of aluminum or other suitable material and held togetherby V suitable meansehere; shown; as pairs ofspaced parallel clamps 4andjl7 engaging the outer faces of the plates 44- .d 45;?Ul3ibeing, held together. by rscrews tfiand nuts 49.

J u v p flthe plateASis very slightly-concave (liig 5:) and 's; formed adjacent itscenterwith-acentral bore; 5 1-; Between tthe inner faces :of the plates is disposeda eXi-hle diaphragrnjz of suitable. material-as vinyl plastic the peripheral, edge -53 of the diaphragm extending outwardlyover the ,p, e'ripheral .edge 54:0fthe-plate- Th dlap ragrn cooperates withlthe innertaces. of the Il aw SWI 2 1 ln2 Ph Q Pressure ,chamberi56 be twe n. the diaphragg nd latens; ,anda cvalve chamber57:

V between'the diapl ragmfand the plate, 45.

The plate 4 l.;is,p rovide l with aplmality; or ports.-58zsoa that ,the atn'iiospheric pressure chamber 56; is .in free com munication with'the atmosphereat alltimesl PlateAA-is", UFflI.P9 -dd h: .nt l rans se o e.-59 t ceive the r duced; end ,of an insulating collar ;60,-..of suitor abl plastic )m' ula't nam tflifl WhiQh isw eet i outer face oftthe;plate 44:,by screwstnot shown.) and is;

7 formed with a central bore to receive an internallyand'w externally threaded bushing 62, The bushing in tumtreceives an; enternallythreaded adjusting screw 63 provided' with a knob; 6,4, the inner endoithescrew,carryingaa Contact 65 Whichis electricallyi connected, through. thescrew 6 3, wire 66,; contact 67 and wire;68 to one wire' ot r i irjcuit diaphragm tomove toward-the innerface of plate-4 5,

ASahdithere held position by the peripheral clamp 55;"

4' V The opposite end of the base of the T coupling threadedly receives a nipple coupling 79 to which is frictionally connected a flexible tube 80"which in turn communicates with the patient in a manner hereinafterto be described.

Disks 82 of suitable material such as rubber are pro- 7 vided on both sides of the diaphragm adjacent its'central portion and carry the other switch contact 83 which extends through the disks and diaphragm and is held in place by a nut 8,4: on thevalve chamber side of the diaphragm. The contact 83 is electrically connected through the Wire 85-, screw 86,- plate'. 45; clamps' 4oand 47 and screws 49c'and plate 4410 the terminal-87 and.--to wire 88, the opposite wire of the circuit. The terminal 67 is insu- V lated from the terminal-37-bysuitablemeans as an insulating plate 89 of suitable insulating material connected to the outer face of plate 44. 7

With reference to Fig. 2, the outer end of the flexible tube 80 may be either connected to the upper lip of the patient directly beneath onenostril by suitablemeans as by astrip of adhesive tape or inserted'in his mouth or as shown irrdot-dash); extend through a holein th'e h'ead" V end of thecasingand thence to the nipple'9lfof the'tubw' larbreathing'belt 92ywhich is strappedi-about'the chest lof i a the-patient; Thebreathing belt-92"comprises a hollow a flexible stripof rubber-tubinghaving 'a' pleated side wall and closed'ends and which when the patients-lungs'andand 71, and conduit 70 into the valve chamber 57, thereby- V to subjects the diaphragm to negativepressure Whenthe patient himself 'initiatesaninhalation. V I

From the foregoingit-is-clear that upon-initiation by thespatient ofrtth'eperiod ofinhalation; the negative-presesure is created in the valve chamber '57 causing/the thereby tocopenitheenormally closed-contacts 65 and 83i During .the period LOf the, patients" inhalation atmospheric-- pressure is allovved to leak'back through port 78, 'needleutomatically to its;norrnal position withthe contacts fiS- V nd,;83a in. closedposition 7 7 Opening. of, the contacts 65zan'd183 dc-energizes the relay-R; to close rtheacircuimT-l, 104; 102, 29-, 101; T2;

' energizing;,the,;solenoid..20 .which1m0vcs thevalve .18ito1 closed position thereby initiating the. negative pressure cycle within the casing to assistv=the pat-ients inhalation during: the remainder QflPfiIiQd :ofiinhalation;

- which; opens ;the first circuit: and closesthe: circuit: T-1. 104,106; 20; 1&1 and. T2,: thereby-causing the: solenoid;

The central bore- 51; of thegplate fi at; its ,outer end;

rece'ves an inte'rnallythreaded metallic bushing 69 which in turn threadedly receiwis t e? inner end} of aconduit .70, thepppositeend of the vconduit being connectedto a, stem of a Tfcouplingfll, One end of the b ase of the, T coupling threadedly; receives a'conduit 73 at the opposite'endc; of whichisponnected by suitable means as .the coupling 74 a; conventional needle valve ;75, the. needle valves-being adjustable through the stem 76 and adiusting knoh77and} having a port 78 in communication with the atmosphere.

totmove; the valve 18 to open-position. This terminates th;:- .g ative pressure; cycle and; causes atmospheric or;

positive; pressure? to; be built up; irrthe. respiratori casinggthus aiding the patient during exhalation.- V c t V V Y c When; the: tube 88 is, :attached lWllh lit'siend adj acentato V the, patientshostril there :is a; space: ,between :itsopen endi'; and the :p atient s nostril-1S0 thatriwhennthepatients lungsz are fullyexpanded nd air ceases to -;be;drawn;in=through: his nose fromthe atmosphere negative pressure isa'no longer created at ,the endof the; tube 80.;and air; under 7 atmospheric pressure enters; the; openilend ofj the, tube.-

connecterLwith; the-patient at his nostril; The sarneeis-r 7 true with-theend of; the

tubejlocatedl between the zpatients lips When the tube 80 is connected with the chest operated member 92, however, the needle valve 75 or its equivalent must be used to create atmospheric pressure in the valve chamber promptly after the patients lungs have been fully expanded at which time the extension of the chest operated member 92 is discontinued.

In all cases the needle .valve is useful to adjust the length of time necessary to neutralize the negative pressure in the chamber 57. The patient can also himself initiate the exhalation cycle by commencing to exhale into the tube, thereby creating positive pressure therein.

From the foregoing description it will be apparent that by utilizing the embodiment of Figs. 1 to 6 the patient himself initiates each period of inhalation and that opera-- tion of the device is much more satisfactory than that of the customary artificial respirator in which periods of inhalation and exhalation of predetermined duration are forced upon the patient.

The embodiment of Fig. 7

The embodiment of Fig. 7 essentially comprises an apparatus wherein the patient normally controls the actuation of the butterfly valve 18 through a patient operated pneumatic switch similar to the one shown in Fig. 6 of the drawings but a second automatic pneumatic switch similar to the one shown in Fig. 3 of applicants copending application Serial No. 416,858, filed March 17, 1954 is provided to take over operation of the valve 18 in the event of failure of the patient operated pneumatic switch.

In this embodiment the pneumatic system represented by the blower 12, conduits 10, 13, 100 and 15, venturi 17, atmospheric port 14 and safety valves 32 and 22 operate in the same manner as described in connection with the embodiment of Fig. 6.

The pneumatically operated switch element 42 is of the construction illustrated in Figs. 1 to 6 of the drawings and the tube 80 is interconnected with the patient either at his nostril, lips or chest in the manner illustrated in Figs. 1 and 2 and as described in connection with the description of the embodiment of Figs. 1 to 6 of the drawings. Pneumatic switches 42 and 190 are adjusted to cooperate with each other so that the apparatus is ordinarily patient controlled by means of switch 42 but in case pneumatic switch 42 becomes inoperative, pneumatic switch 190 automatically takes over to automatically control the breathing cycle.

The second double acting automatic, pneumatic switch 190 is mounted in the housing 122 and is located in the lower chamber 124 thereof. The port 125 afiords continuous communication between the interior of the chamber 124 and the atmosphere.

The diaphragm 126, made of rubberized fabric or other suitable flexible material, has its edge secured to the housing 122 and it forms one wall of the substantially air-tight chamber 132.

The switch arm 153 is mounted for pivotal movement about the axis 160 and it is normally retained in the position illustrated in Fig. 7 by the permanent magnet 156. When it is in said position one of the circuits hereafter described is closed by the spring pressed plunger 154. When the switch arm is moved upwardly a sufficient distance about the axis 160 the spring pressed plunger 154 is elevated by the spring (not shown) and this action opens the first mentioned circuit and closes another circuit.

The arm 153 is elevated about its pivotal connection by the wire 151, the lower end of which is secured about the switch arm 153 and the upper end of which is attached to the center of the diaphragm 126.

When sufiicient negative pressure is created in the chamber 132, said negative pressure acts upon the center of the diaphragm 126 and moves it upwardly a sufficient distance so that the lower end of the wire 151 elevates the free end of the switch arm 153 and it snaps away from the magnet 156, thus permitting the plunger -v 154 to move upwardly following the arm.

When the negative pressure in the chamber 132is neutralized to substantially atmospheric pressure or to plunger 154 and causes another circuit to be energized" as more fully described hereafter.

The interior of the chamber 132 is connected to the interior of the respirator casing 1 by the transfer conduit 150, one end of which communicates with the top of the valve chamber 132 and the other end of which is provided with a slight flared portion 162 which, in the embodiment illustrated, is located in the atmospheric conduit 13 so that it may more readily receive atmospheric and positive pressure created in the atmospheric conduit.

The transfer conduit 150 is provided with a negative pressure by-pass conduit 165 and an atmospheric by-pass conduit 170. The check valve 166 in the negative pressure by-pass conduit is normally closed but it is opened by the creation of negative pressure in the negative pressure by-pass 165 and it is automatically closed when the pressure in said by-pass is returned to at least substantially atmospheric pressure. The valve 167 located in the negative pressure by-pass may be a needle valve or any other means for controlling the effective size of the passage in the negative pressure by-pass.

The check valve 171 is opened by the creation of substantially atmospheric or positive pressures in the atmospheric by-pass conduit 170 and is closed by negative pressure therein. The valve 172 in the atmospheric by-pass may be a needle valve or any other means for controlling the effective size of the passage in the atmospheric bypass 170.

The valve 175 located in the transfer conduit 150 may be a needle valve or any other means for controlling the effective size of the passage in the transfer conduit.

As in the embodiment illustrated in Fig. 6 of the drawings, the valve 32 functions as a leak for positive pressure created in the conduit 100. It consists of the plate 34, regulating screw 33, port 30 and the valve 32 which is pivotally connected to the conduit at one end. It serves to control the maximum amount of positive pressure created within the respirator casing.

With the butterfly valve 18 in closed position, the negative pressure creating means 12 creates negative pressure in the respirator casing, causing a period of inhalation by the user. At the same time, negative pressure is created in the transfer conduit and in the by-pass conduits and 170. The negative pressure in the atmospheric by-pass closes the check valve 171 whereas the negative pressure in the negative pressure by-pass 165 opens the check valve 166 so that negative pressure is transmitted to the chamber 132 of the pneumatic switch element.

Eventually suflicient negative pressure is built up in the chamber 132 to elevate the center of the diaphragm 126, the outer end of the switch arm 153 and the contact plunger 154. The amount of time required to build up the required amount of negative pressure in the chamber 132 depends upon the adjustment of the needle valve 167.

When the switch arm 153 is thus elevated by the diaphragm 126, a circuit is completed through the double acting solenoid 20 as hereafter described and it opens the butterfly valve 18. This terminates the period of inhalation by the user and permits air under positive pressure to flow from the venturi 17 and port 14 through the atmospheric conduit 13 and the conduit 100 to the interior of the respirator casing 1, thus neutralizing the" pressure to enter the transfer conduit 150 and to neutralize thenegativepressure theretoforepresent thercin,

This air under positivepressurecloses the check ivalve 16 6 and cpens the'checkvalve "1'71and itpasses throughthe atmosplferie-by-passflt] andthence; to the valve-chamber 132= ofii'the pneumatically operated-switch: Eventually- 1t'-neutral1zes--thenegative pressure previouslybuiltup; in;

, the-chamber 132; and the "pressure therein becomes' substantiall'y positivee Theicenter offthe'diaphragm flfi then" ls returned to'itslowered position and the wirejifrl moves-- the free end of the switch armf153 downwardl'y*tothposition shown in Fig; 8: Theamount of time required for-"thisoperatiori 'depends upon the adjustment of theneedleva1ve-172 -since saidivalve controls" the rate of-flovv' ofgas through the conduit 170i- When. the-switchgai m 153 has: been" returnedto its lowered positienj the-contact plunger 154' is lowered, the 'circuit previously energized is opened and another circuit'hereafter described is ;c1 osedj which causes a the solenoid' 20 to-rotate-th'e butterflyvalyie-IS to closed position} This shuts-olfthe-supplyof positive pressureinth'e atmospheric: conduit-'13 and; causes" the exhaust from-- the venturi-TI' to be vented to the atmosphere through' the port14'. Negative pressure is DQW-bl1l1tfUp'in'th6ICS- pirator casing 1- by theysuction blower-'12, the period er exhalation-is terminated and the" next period ofinhalation is commenced;

" From- -the= foregoing' description; it will be understood that the needle valves '16 7 and-172 may bemanipulated to provide a longerperiod of-inhalationthan ofexhalation or vice versa.

Theneedlewalve 175 located in thetransfer conduit" 150 may be usedto'adjustthe-duration of the combined periods of-exhalation'and-of-inhalation; Whenthe'needle valve; 175 is adjusted towardclosed position; gas-t passes through thetransfer conduit 150-aha smaller volume per-- unit of time and consequently the duration of the -com= bined periodsof" exhalation and'in'halationis increased.

Conversely; when the valve 175' is adjusted-toward open positiomthe duration'ofthecombined periodscfexhahtion and" inhalationis decreased" because-gas passes through the transfer conduit ingreater 'volume-duringa givenperiod'of time.

From-the foregoing-description;it will be understood blower-"12. Upon=theinitiation-of a pieriod-ofinhalation byth'e patient, negative pressure is created inthe valve chamber 57*of=the pneumaticallyoperated switch- 42 througlr the tube 80 and said'pressure opens the contacts 65; Siflby-mov-ing the center of the: diaphragm-52 in-- substantiallyatmospheric-pressure whereupon thediaphragm 52 automatieally returns to its' normal"- position closing the contacts 65and 83'r This causes the circuit- T1, 1033K; 201 190, 200, 68;" 65,- 83 '88, and 'mjto be;

V 20, 101, ,and Tzjtherehyhcausing thesolenoid tomoye'thje valve lfi to openposition: This terminates thenegative pressurecycle andcausesatmospheric or positive pressure V to;bc huilt 'up im the' r'espirator casing Ifthus aiding patientgduring exhalation;

ofaicledinhalationz howevenbecause the p atienlhimselfjsg unahlejto initiate 7 wardlyoi the valve chamber 57. This opens the circuit T1;' 103',-'R, 201-, 190, 20%;: 6 3, $3,- 88 and T2. Opening thiscircuit-causestherelayto'close the circuit-T1; 103;:104, Hi2, 29, 191 and TZ energiZing thesoleuoid-Zil} which-moves the-butterfly valve '18 to 'closedp osition,

tliereb'y' initiating --the --negative pressure cycle within the casing l-to assistthepatients inhalation during-the remainder ofthe-period-of inhalation. p

'D'uring the-period of inhalation, atmosph eric pressure. is allowed tO-leak-througlithe-needle valve -into the valve-chamber-fijTto nearly counteract the-negative-pres sure=-whichcontinues to lac-transmitted to '[llflChEl-Hlbfil" 57 throughthe-tube 8 Upon termination of-the normal expanded and thecreation of negative pressurein the tube-- 'either at the patientsnose, or;-'iips on by the member 92 about his -chest-"(depending upon which con nection is-=used) f is' discontinued and the -pressure-withiri When the'periodfof-exlialation'has been completed; the

p atient agaiininitiates a:,period"of inhalatiommoving' the diaphragmv52finwardly-of the valve chamberS'Z-andopenj By meanstofthe'needle valve 175-in the'itransfer con:

duit ;the auxiliary pneumatioswitch-190may; head r 7 justed to take over operation of thevalve'l8i For'ex ample, when a patient normallysbreathes.eighteen times w tchl90;'is.. kw se n perative,

- P9: m nute, y. ntro i he np ratua ou h the tentrtliat when the butterflyvalve .l 8"is under operatioupf' the pneumatic switchi 190 thmugh1thetransfer duit, 150, it willproduce, twelveihreathing cycles per minute;t.

pneumaticpswitch 42 producingeighteenbreathing cycles; per minute-.1 under control ofth'e, patient, the pneumatic switch 19.0,dos not function .while the switchi42 is tune;-

tioning because during'each period? of inhalation insuflif-P cient ncgative pressure, is built up,inithetvalve chamher 1321(toacituateitlie diaphragm 1 26; suificiently to. operate the switch .19.0.1 During each; period, of exhalation ,7 the When the pneumatic switch;,;42',becqmes inoperatij ie,

aritiuhalation oi: ,for any, other} reason, the contalctsjfi andQSS'IeInain in..,nor;mal clq: S!?.,d. position, the switch 190 takes ,oyer, controlof the vbutteiifly ivalve 18 through; ,the relay tandfpro dilces respiration atthe rate of' twelve cyclesper minuteoraat whatever, rater thetvalve has,

been. set to produce.v valve. 18,. open, 2 positive, pressure is transmitted to the, respiratory casing and,. through the transfer dui 150,

valve ,175, positive bypasses .170, valve 171 and, thence: to.; the. chamber 132;, When; suflicient positive pressure builds up'in the chamber 132Lthediaphragm12 6jis moved,

downwardly and .causesthe contacts of the, switch 190. to be opened. This;opens thegcircuit-Tl, 103, R, 2701, 190, 200,,68-,.65,,83, 88,,and ,T2 and causes the relay to close,

the, cir cuit.T1, 103, 109,102,20, 101 and I2energizingf. the solenoid 20 which movesthe, butterflyvalvelS; to,

closed position, thereby, initiating, the, negative pressure cycle withinthecasing 1 to producean inhalation.

p, with the valve 18 closedandqnegative pressure created within the respirator casing hyathesuction blower,

60 19,0, 200, 68,- 65, 33,381andT2 and relay thencloses the circuitTI, i103; 104,{10 6,i20; 101'and T2 th'ereb'y causing' the solenoidgto move the,1valve 18 ,to ,open positiong 1 a;

terminates the negativepressure cycleand causestpositiye,

pressuregto, bejbuilt upin the. respirator casing thius aide, 1

" ing the patient during exhalation.

From the foregoing description,it,will.be apparent that the apparatusof Figfl'provides an artificial respiratorwith;

1 two pneumatic controls, one. operatedby thepatienthimperiod-of inl-lalationthepatients-lungs -and' chestare fully- 79 5 l i Q QIm l YJHL flfl df flqth l pe ated;

' by-a pneumatictsystemconnected w th'thesluteriorcfathe respirator: casing 1 and which functions in-- the :event the:,. patient becomes, unable to t initiate inhalation himself-5 or: in =the-event the fir 'st pneumatic control fails to function; a

, the valve chamber 57*is-almost'dnnnediately-returnedto- 75=fonanywther reasons Under, such operation, with, V

Other suitable pressure responsive members may be substituted for the diaphragms 52 and 126.

It should be understood that the pressure in chamber 132 can be cyclically controlled in accordance with the manner shown in Fig. 2 of applicants copending application Serial No. 416,858, rather than by the construction shown in Fig. 7.

While in the embodiment of Fig. 8 positive pressure enters the end 162 of the transfer conduit 150 the apparatus will function equally well if alternate cycles of negative and substantially atmospheric pressures are used as in the embodiment disclosed in Fig. 2 of applicants copending application Serial No. 416,858, filed March 7, 1954.

While I have shown and described embodiments of the invention, it is to be understood that this disclosure is for the purpose of illustration only and that various changes and the substitution of equivalent elements may be made without departing from the spirit and scope of the invention as set forth in the appended claims.

I claim:

1. Apparatus for producing artificial respiration comprising a substantially air-tight respirator casing to receive and enclose at least part of the users chest but with his head exposed to the atmosphere, means for continuously creating negative pressure, a negative pressure conduit having one end communicating with said pressure creating means and the other end communicating with the interior of the casing, an atmospheric conduit providing communication between the interior of the casing and the atmosphere, a valve in the atmospheric conduit movable to open and closed positions and which, when in open position, admits gas from the atmosphere through the atmospheric conduit to the casing to assist the users exhalation and substantially to neutralize the negative pressure created in the casing by said pressure creating means during each period of inhalation, electrically operated means to actuate said valve, and a pneumatically operated switch for controlling said electrically operated means, a tube for interconnecting the user with the pneumatically operated switch, said tube adapted to be so connected to the user that initial expansion of the users lungs upon the intiation by the user of an inhalation creates negative pressure in said tube, and a diaphragm in said pneumatically operated switch which is actuated by said negative pressure to control the circuit to said electrically operated means whereby said valve is closed upon the initiation of each period of inhalation by the user thus causing negative pressure to be created in the casing by said negative pressure creating means thereby to aid the user during the remainder of each period of inhalation.

2. The combination of claim 1 also comprising a substantially air-tight chamber on one side of the diaphragm of said pneumatically operated switch, one end of said user interconnecting tube communicating with said chamber, a passage providing communication between said chamber and the atmosphere and means for controlling the effective size of said passage, whereby after the cessation of the creation of negative pressure at the user end of said tube the pressure in said chamber is returned to at least substantially atmospheric pressure by the flow of air through said passage from the atmosphere.

3. Apparatus for producing artificial respiration comprising a substantially air-tight respirator casing to receive and enclose at least part of the users chest but with his head exposed to the atmosphere, means for continuously creating negative pressure, a negative pressure conduit having one end communicating with said pressure creating means and the other end communicating with the interior of the casing, an atmospheric conduit providing communication between the interior of the casing and the atmosphere, a valve in the atmospheric conduit movable to open and closed positions and which, when in open position, admits gas from the atmosphere through the atmospheric conduit to the casing to assist the users exhalation and substantially to neutralize the negative,

pressure created in the casing by said pressure creating means during each period of inhalation, electrically operated means to actuate said valve, and a pneumatically operated switch for controlling said electrically operated means, a tube for interconnecting the user with said pneumatically operated switch, said tube adapted to be so connected to the user that initial expansion of the users lungs upon the initiation by the user of an inhalation creates negative pressure in said tube, a diaphragm in said pneumatically operated switch which is actuated by said negative pressure to control a circuit to said electrically operated means, whereby said valve is adapted to be closed upon the initiation of each period of inhalation by the user, thereby to aid the user during the remainder of each period of inhalation, a second pneumatically operated switch for controlling said electrically operated means when said first pneumatically operated switch fails to function for a predetermined period of time, a transfer conduit providing communication between said second pneumatically operated switch and the interior of the casing, a check valve in said conduit which is moved to open position by negative pressure in the conduit and to closed position by at least substantially atmospheric pressure in the conduit, whereby said second switch is adapted to be moved in one direction by negative pressure created in said transfer circuit by said means for continuously creating negative pressure.

4. The combination of claim 3 also comprising a substantially air-tight chamber on one side of the diaphragm of said first pneumatically operated switch, one end of said user interconnecting tube communicating with said chamber, a passage providing communication between said chamber and the atmosphere and means for controlling the efiective size of said passage, whereby after the cessation of the creation of negative pressure at the user end of said tube the pressure in said chamber is returned to at least substantially atmospheric pressure by the fiow of air through said passage from the atmosphere.

5. Apparatus for producing artificial'respiration comprising a substantially air-tight respirator casing to receive and enclose at least part of the users chest but with his head exposed to the atmosphere, means for continuously creating negative pressure, a negative pressure conduit having one end communicating with said pressure creating means and the other end communicating with the interior of the casing, an atmospheric conduit providing communication between the interior of the casing and the atmosphere, a valve in the atmospheric conduit movable to open and closed positions and which, when in open position, admits gas from the atmosphere through the atmospheric conduit to the casing to assist the users exhalation and substantially to neutralize the negative pressure created in the casing by said pressure creating means during each period of inhalation, electrically Operated means to actuate said valve, and a pneumatically operated switch for controlling said electrically operated means, a tube for interconnecting the user with said first pneumatically operated switch, said tube adapted to be so connected to the user that initial expansion of the users lungs upon the initiation by the user of an inhalation creates negative pressure in said tube, a diaphragm in said pneumatically operated switch which is actuated by said negative pressure to control a circuit to said electrically operated means, whereby said valve is adapted to be closed upon the initiation of each period of inhalation by the user, thereby to aid the user during the remainder of each period of inhalation, a second pneumatically op erated switch for controlling said electrically operated means when said first pneumatically operated switch fails to function for a predetermined period of time, a transfer conduit providing communication between said second pneumatically operated switch and the interior of the casing, a check valve in said conduit which is moved to open position by negative pressure in the conduit and to closed position by at least substantially atmospheric pressure in ass- 4,348

the conduit and means for controlling the "efie'ctive size of thejransferfc'onduit, wherebyfthje anioujntfof timenecessaryff or 'sufiicient negative pressure 'to be "transmitted through said transfer conduit to the second pneumatically operated switch may be adjusted so that the second switch will not operate to control said "electrically operated 'm eansuntil a predetermined period of time has elapsed during which said first pneumatically operated switch fails to control-said electrically operated means.

7 v 6; Apparatus forproducing artificial respiration comprising a substantially air-tight respirator casing to re ,ceiveand "enclose at least part of the'users chest but with his h'e'ad'exposed' to the atmosphere, means for continuouslyc'reating negative pressure, a negativeipressure conduit having-bne end communicating. with said pressure creating'm'eans and theotherend communicating with theinterior "of the casing, anatmospheric conduit providing communication between the interior'ofthe casing an'd the atmosphere, a v'alvein the atmospheric conduit a movable toiopen' and closed positions and which, when in open'pesitien;admits 'gas from the atmosphere through theatmospheric conduit to the gcasing to assist'the users exhalation and substantially to neutralize the negative pressure created inthe casing bysaid pressure creating r'neansfduring each period of inhalation, electrically op- V erated means to actuate said' valve, and a pneumatically in saidpneumatically operated switch which is actuated bysaid negative pressure to control a circuit to said electrically' operated means, whereby said valve is adapted to beclosed by initiation of each period of inhalation'by the 'user, thereby to aid the user during the remainder of each period of inhalation, a second pneumatically operated switch for controlling said electrically operated means when said first pneumatically operated switch fails to function for a predetermined period of time, a' transfer conduit providing communication between said second pneumatically operated switch and .the interior of the casing, "a negative pressure by-pass conduit in said transfer conduit, an atmospheric by-pass conduit in said trans- V for conduit, a negative-pressure check valvein said negative pressure by-pass conduit which is moved to open position by negative pressure in said negative pressure by-pass conduit and to closed position by at least sub: stant'ially atmospheric pressure therein, a substantially atmospheric pressure check valve in said atmospheric bypa'ss conduit which is moved to open position by at least substantia'lly atmospheric pressure in 'saidjatmosph'eric by-pass conduit and to closed position by negative p'ressuretherein, whereby said switch is adapted to be moved in one direction by negative pressure created in said negative pressure bypass conduit and in the other direction "byat least substantially atmospheric pressure created in said atmospheric by-pass conduit and means for controlling the effective size of the transfer. conduit.

7. Apparatus for-producing artificial respiration comprising, a' substantially, air-tight respirator casing to receive and enclose at least part of the users chest but with his head exp'osedto the atmosphere,'rneans for 'continuously' creating negativepressum, a negative pressure conduit'having one end communicating withrsaid pressu're creating means and-the other end communicating with t the interior of the casing, an atmosphericconduit promeans during each period of inhalation, electrically op-' erated means to actuate "said valve,' a'nd a pneumatically operated switch for controllingsaid electricallyoperated means, ;a tube for; interconnecting the user said prieumati'c'ally operated 'switch, saidgtube adapted to be so connectedtothe'user that initialiexpansion of the user-3s lungs upon the initiation by the user of'an inhalation "creates negative pressure in said tube, a diaphragm in said pneumatically operated switch which is actuated by said neg'ative pressure to control a circuit to said electrically operated means, whereby said valve is 'ad apted to be closed uponthe initiation of'each period of 'inhala: tion by the user, thereby. to aidthe user during the reinainder of each period of inhalation, a second pneujmatic'ally' operated switch for controlling said electrically operatedjmeans when said first pneumatically operated switch fails to functionfor a predetermined period of time a transfenconduit providingf communication ,be-j

' tween said pneumatically operated switch andthe interior of the casing,ra negative pressure-by-pass conduit in said transfer conduit, an atmospheric bypass conduit insaidtransfer, conduit, a negative pressure checkyalvein said negative pressure by-pass conduit which'is moved to open position by negative pressure "in said negative --pressure by-pass conduit and toclosedpositioh 'by'atfleast sub- 'stantially atmospheric pressure thereinya substantially atmospheric pressure check valve in "said atmosphericfbypass conduit which is moved to open position by;at least substantially atmosphericpressure in said atmospheric by-pass conduit and to closed position-by negative pres sure thereimmeans for'controlling the efiective sizeof the passage of the negative pressure by-pass, means for f controlling the effective size of the passage of the "atmospheric pressure by-pass andme'an's for controlling the efiective size of the transfer conduit, whereby the amount of time'necessary to build up sufiicientnegative pressure in said transferconduit to operate said second pneum'at ically operated switch and the amount of time necessary to build up suflicient atmospheric or positive pressure to operate said second pneumatically operated's'witch may be controlled so that said second pneumatically operated switch controls said electrically operated means only when said first pneumatically'operated switchfails to 7 function for a predeterminedyperiod of time.

tion, admits at least atmospheric pressure to. the casing to 8. Apparatus for producing artificial respiration conition, an atmospheric pressure conduit providing c'ommunication'between the interiorof'the casing andthe-atrnos phere, a valve in the atmospheric conduit movable to open and closed positions and which, when in open posiassist the users exhalation, a firstpressure"responsive control means, a passage interconnecting the user with the first pressure responsive control means, one end of said passage adapted'to be so connected to the us e'ras' to V expose the firstvpressnre responsive control to negative pressure by the initiation of an inhalation by the'user,

said first p'ressure' control meansbeing op'e'ra'tive to close 7 the valve upon the initiation ofeach period of inhalation by the user and to open the'v'alveupon the termination l of each period of inhalation, a second pressure responsive control rneari's, a transfrfconduit':interconneeting the atmosp'heric conduit with 'the second pressure-responsive control means, for exposing the second pressure res onsive control rneanstopredetermined-variations of thepresi sure in theatm'osph'eric conduitfanjd adiustable'va'lves in the "transfer conduit for regulating the flow et-gas existing in's'aid trans-fer conduit at' saidpre'deterniine'd variations of pressure through said transfer-conduit-ata "predetermined rate so' as to expose the see'o'rid pressure respousive cont-fo1 means theieto at predetermined inter-- than the rate of the periods of initiation of inhalation and exhalation by the user, said second pressure responsive control means being responsive to said predetermined variations of pressure in the atmospheric conduit and operative to close and open the valve at predetermined intervals upon the first pressure responsive control means becoming inoperative because of the inability of the user to initiate the period of inhalation.

9. Apparatus for producing artificial respiration comprising a substantially air-tight respirator casing to receive and enclose at least part of the users chest but with his head exposed to the atmosphere. a negative pressure conduit communicating with the casing, suction means connected to the negative pressure conduit for creating negative pressure within the casing to assist the users inhalation, an atmospheric conduit having communication between the interior of the casing and the atmosphere or a source of positive pressure, a valve in the atmospheric conduit movable to open and closed position and which, when in open position, admits at least substantially atmospheric or positive pressure to the casing to assist the users exhalation, and pressure responsive control means including a diaphragm and a diaphragm operated switch, electrical means for opening and closing the valve and a circuit electrically interconnecting the switch with said electrical means, the switch when closed being operative to close the circuit to energize said electrical means and to open the valve, and the switch when open being operative to open the circuit to de-energize the electrical means and to close the valve, means for pneumatically interconnecting the user with the diaphragm and constructed and arranged so as to expose the diaphragm to variations of the pressure in the users lungs, said diaphragm being movable in response to said variations in pressure to open the switch upon the initiation of each period of inhalation by the user.

10. Apparatus for producing artificial respiration comprising a respirator casing to receive and enclose at least part of the users chest and adapted to give the user access to the atmosphere for breathing purposes, means for creating a negative pressure, a source of positive or atmospheric pressure, a conduit system afiording communication between the interior of said casing, said means for creating negative pressure and said source of pressure, valve means in said conduit system adapted to be operated to alternately afford operative communication between the interior of said casing and said means for creating negative pressure and said source of pressure, means for controlling the operation of said valve means through a time cycle comprising two alternating time periods, during one of which periods said valve means is actuated to provide operative communication between the interior of said casing and said means for creating negative pressure to produce within said casing a negative pressure whereby inhalation is induced in the user, and during the other of said time periods, said valve means is actuated to provide operative communication between the interior of said casing and said source of pressure to produce substantially atmospheric or positive pressure within the interior of said casing, whereby exhalation occurs, said control means comprising means for actuating said valve means to initiate said negative pressure period of said cycle in response to initiation by the user of each inhalation and to actuate said valve means to terminate said negative pressure period and initiate the other pressure period of said cycle after termination of said inhalation.

11. The apparatus of claim including a second means for controlling the operation of said valve means through a cycle similar to said first mentioned cycle when the first valve control means fails to function for a predetermined time, said second valve control means comprising means responsive to variations in pressure, within the interior of said casing for actuating said valve means through said similar cycle when said first valve control means fails to function for a predetermined time.

12. Apparatus for producing artificial respiration comprising a substantially air-tight respirator casing to receive and enclose at least part of the users chest but adapted to give the user access to the atmosphere for breathing purposes, means for transmitting negative pressure to the interior of said casing to induce inhalation in the user, means for transmitting positive or atmospheric pressure to the interior of said casing whereby exhalation occurs without any efiort on the part of the user, valve means associated with said pressure transmitting means and adapted to be operated to alternately provide for the transmission of said negative pressure and said positive or atmospheric pressure to said interior, pneumatic means, responsive to initiation by the user of each inhalation when said pneumatic means is operably connected with the user, for operating said valve means through a time cycle comprising two alternating periods, during one of which periods said valve means is actuated to provide for said transmission of negative pressure to said casing, whereby completion of said inhalation is in duced and during the other of said periods said valve means is actuated to provide for the transmission of said positive or atmospheric pressure to said casing, whereby exhalation occurs with no effort on the part of the user.

13. Apparatus for producing artificial respiration comprising a substantially air-tight respirator casing to receive and enclose at least part of the users chest but adapted to give the user access to the atmosphere for breathing purposes, means for transmitting negative pressure to the interior of said casing to induce inhalation in the user, means for transmitting positive or atmospheric pressure to the interior of said casing whereby exhalation occurs without efiort on the part of the user, valve means associated with said pressure transmitting means and adapted to be operated to alternately provide for the transmission of said negative pressure and said positive or atmospheric pressure to said interior, first means for controlling the operation of said valve means through a time cycle comprising two alternating periods, during one of which periods said valve means is actuated to provide for the transmission of negative pressure to the interior of said casing to induce inhalation in the user and during the other of said periods said valve means is actuated to provide for the transmission of positive or atmospheric pressure to said interior, whereby exhalation occurs, said means for controlling the operation of said valve means including a chamber, means responsive to pressure variations in said chamber for operating said valve means, means, responsive to the initial expansion of the users lungs upon initiation by the user of an inhalation, for creating negative pressure in said chamber, said valve operating means being responsive to said creation of negative pressure in said chamber to actuate said valve means to initiate a negative pressure period of said cycle and induce the completion of said inhalation without further eifort on the part of the user, second means for automatically controlling the operation of said valve means through a cycle similar to the first mentioned cycle when said first valve control means fails to function for a predetermined period of time, said second valve con trol means including a second chamber, means, responsive to variations of pressure in said second chamber when said first valve control means fails to function for a predetermined period of time, for automatically operating said valve means through said similar time cycle, and means responsive to pressure variations within the interior of said casing for varying the pressure in said second chamber to automatically and cyclically actuate said second valve operating means through said similar cycle when said first valve control means fails to function for a predetermined period of time, said means for varying the pressure in said second chamber including conduit means providing for the flow of gases into and out of said second chamber, said last mentioned conduit ceive and enclose at least part of the users' chest but adapted to give the user access to the atmosphere for breathing purposes, means for transmitting negative pressure to the interior ofmsaid casing to induce inhalation in the user, means for transmitting positive or atmospheric pressure to the interior of said casing to induce exhalation in the user, valve means associated with said pressure transmitting means and adapted to be operated to alternately provide for the transmission of said negative pressure and saidpositive or atmospheric pressure to saidtinterior, means for controlling the operation of said valve means through a time cycle comprising two alternating periods, during one of which periods said valve means is'actuated to provide for the transmission of negative pressure to the interior of said casing and to induce inhalation in the user and during the other of said periodsisaid valve means is actuated to provide for the transmission of positive or atmospheric pressure to the interior of said casing whereby exhalation occurs without any eiiort on the part of the user,-said valve concompletion of said inhalation is induced without further effort on the part of the user when said respirator casing is operably connected with said user and means responsive to the termination of said inhalation to actuate said a diiferent magnitude to said delivery conduit means, valve means associated with said pressure transmitting meansand adapted to be operated to, alternately provide for the transmission of said pressure of one magnitude and said pressure of a different magnitude to said delivery conduit means, pneumatic means/responsive to initiation by the user of each inhalation when said pneumatic meansv is operably connected to the user, for operating said valve means through a time cycle comprising two alternating of one magnitude to said delivery conduit means and during the other of said periods said valve means is acmated to provide for transmission of said pressure'of a different magnitude to said delivery conduit means, sec- 0nd pneumatic means for automatically actuating said valve means through a cycle similar tosaid first'mentioned cycle when said first pneumatic means fails to'function for a predetermined time. V

16. A valve apparatus for cyclically producing alter: nating pressures of diflerent magnitudes in apparatus for treating users comprising delivery conduit means, a first port for communication with a first source of pressure of one magnitude, a second port for communication with a second source of pressure of a different magnitude, aconduit system for affording operative communication between said first port and said delivery conduit means and between said second portand said delivery conduit means,

valve means to alternately provide forthe transmission of a pressureof one magnitude-from said first port through aid conduit system to said'delivery conduit means, whereby inhalation is automatically induced intsaid user-when .deliyeiyjconduit means is operably connected With periods, during one of which peridds said valve means is actuated to provide for the transmission of said pressure the user and for the transmission of a pressure of a different magnitude-from said second port through, said conduit system tosaid delivery conduit means, whereby exhalation occurs with no effort on the part of the user, pressure sensitive means for actuating said valve means, said pressure sensitive means being remote from'the flow path of gas flowing between said delivery conduit means and the port from which the pressure of greater magnitude is transmitted while said pressure of greater magnitude is being transmitted to said delivry'conduit means, 'means V for transmitting negative pressure created by initiation of an inhalation by the user to said pressure sensitive means when said pressure sensitive means is operatively connected to-said user, said pressure sensitive meansbeing responsive'to said transmission of said negative pressure thereto to actuate said valve means to provide for said transmission of pressure of one magnitude from said'first port to said delivery conduit means to automatically induce the completion of said inhalation without further effort, on the part of the user, said pressure sensitive means also being responsive to the completion of said inhalation to automatically actuate said valve means to provide for said transmission of a pressure of a different magnitude from. said second port to" said delivery conduit means, whereby exhalation occurs with no effort on the part of the user.

17. The apparatus of claim 16 including second pressure sensitive means, responsive to variations of pressure in said delivery conduit means, for automatically actuating saidvalve means through a time cycle comprising two alternating periods when said first pressure sensitive means fails to function for a predetermined time, during one of whichperlods said valve means is actuated to provide for thetransrni'ssion of a pressure of one magnitude from said first port to said delivery conduit means and during the other of said periods said'valve means is actuated to provide for the transmission of a pressure ofa said second port and said delivery conduit means, valve means to alternately provide for the transmission of pressure of one magnitude from said first port through'said conduit system to said delivery conduit means,'whereby inhalation. is induced in the user when he is operably connected. with said. delivery conduit means, and for the, transmission of pressure of atdilierentmagnitude from said second port through said conduit system to said delivery conduit means, whereby exhalation occurs without efiort on the partof theuser, a control chamber remote from the flow: path of gas flowing between said delivery conduit means and'the'port from which the pressure of grater-magnitude, is transmitted to said delivery conduit meanswhile said pressure of greater magnitude is being transmitted to said delivery conduit means, means responsivel to pressure variations in said chamber :for operating saidfvalve means, means for transmitting negative pres.- surecreated by an initiation of inhalation by the userto said chamber when said chamber is operatively connected to the user, said valve operating means being responsive to said transmission, of negative pressure tosaid chamber to actuateisaid valve means to providefo'r said transmis sion of pressure of one magnitude from said'fir'st port tosaid delivery conduit means to thereby automatically ini duce the completion of said' inhalation without further circu t on the part of the user when said deliveryconduit meansisoperablyconnected with saidiuser; 7

19; Apparatus for cyclically producing alternating pres sures of difierent magnitudes in apparatus for treating users comprising delivery conduit means, means for transmitting pressure of one magnitude to said delivery conduit means, means for transmitting pressure of a difierent magnitude to said delivery conduit means, valve means associated with said pressure transmitting means and adapted to be operated to alternately provide 'for the transmission of said pressure of one magnitude and said pressure of a difierent magnitude to said delivery conduit means, a chamber, means responsive to pressure variations in said chamber for operating said valve means, means responsive to the initiation of an inhalation by the user to vary the pressure in said chamber when said chamber is operably connected to the user, said valve operating means being responsive to said variation in pressure in said chamber caused by said initiation of inhalation by the user to actuate said valve means to provide for the transmission of said pressure of one magnitude to said delivery conduit means whereby the completion of said inhalation is automatically induced without further etfort on the part of the user, and means responsive to termination of said inhalation for thereafter automatically actuating said valve means to provide for the transmission of said pressure of a different magnitude to said delivery conduit means, whereby exhalation occurs without effort on the part of the user and means for automatically operating said valve means through a time cycle comprising two alternating periods when a predetermined time has elapsed without the initiation of an inhalation by the user, during one of such periods such valve means is actuated to provide for the transmission of said pressure of one magnitude to said delivery conduit means and during the other of said periods said valve means is actuated to provide for the transmission of said pressure of a diiferent magnitude to said delivery conduit means, said last mentioned means for automatically operating said valve means comprising a second control chamber, means for actuating said valve means through said last mentioned cycle in response to pressure variations in said second chamber, means for varying the pressure in said second chamber in response to pressure variations in said delivery conduit means, said last mentioned means including transfer conduit means for permitting the flow of gas into and out of said second chamber said transfer conduit means having means for restricting size thereof and hence the rate of flow therethrough to a rate which is substantially less than the rate of flow through said valve means.

the operable 20. A valve apparatus for cyclically producing alternating negative and positive or atmospheric pressures in apparatus for treating users comprising, delivery conduit means, a source of positive or atmospheric pressure, a source of negative pressure less than the pressure of the surrounding atmosphere, a conduit system affording communication between said negative and positive or atmospheric sources of pressure and said delivery conduit means, valve means in said conduit system to alternately afford operative communication between said delivery conduit means and said positive or atmospheric pressure source and between said delivery conduit means and said negative pressure source, whereby said pressures are alternately delivered to said delivery conduit means, pneumatic means responsive to initiation of each inhalation by the user for operating said valve means without further effort on the part of the user through a time cycle comprising two alternating periods, during one of which periods said valve means is actuated to provide operative communication between said delivery conduit means and said source of positive or atmospheric pressure and during the other of said periods said valve means is actuated to provide operative communication between said delivery conduit means and said source of negative pressure.

21. The apparatus of claim 20 including second pneumatic means for automatically actuating said valve means through a cycle similar to said first mentioned cycle when said first pneumatic means fails to function for a predetermined time.

22. The apparatus of claim 14 wherein said means for actuating said valve means to terminate said inhalation period and initiate said exhalation period comprises transfer conduit means for communicating between said chamber and a source of gas, said transfer conduit means having means for restricting the operable size thereof and hence the rate of gas flow therethrough.

23. The apparatus of claim 14 wherein said means for actuating said valve means to terminate said inhalation period and initiate said exhalation period is responsive to the resistance of the users lungs to flow of gas thereinto.

References Cited in the file of this patent UNITED STATES PATENTS 402,779 Steinhott May 7, 1889 2,223,570 McMillin Dec. 3, 1940 2,288,436 Cahan June 30, 1942 2,588,192 Akerman Mar. 4, 1952 

